1. Field of the Invention
Embodiments of the present invention relate to a hard disk drive, and more particularly, to a hard disk drive and method parking a read/write head to minimize deformation of a ramp end tab, generated as the end tab bumps against a lateral surface of an end tab limiter when a head stack assembly (HSA) is assembled on a base while the end tab is located at an initial assembly position of the ramp.
2. Description of the Related Art
Hard disk drives (HDDs) are recording and reproducing apparatuses for writing/reading data to/from a disk using a read/write head. HDDs are presently widely being used as auxiliary storage devices for computer systems due to their ability to access a large amount of data at high speeds.
Recently, HDD capacities have been increasing with the increases in the number of tracks per inch (TPI) (representing a density of the hard disk in a disk radial direction) and the number of bits per inch (BPI) (representing a density of the hard disk in a disk rotational direction). With such increases in capacities, the available application range for HDDs also has been extended. Further, HDDs have also been shrinking in size for use in portable electronic devices, such as in notebook computers, personal digital assistants (PDAs), and mobile phones. For example, 2.5 inch HDDs have been developed for such notebook computers. Similarly, an ultra-compact HDD having a diameter of 0.85 inches, for example, similar to that of a coin, is actively under development for use in mobile phones.
HDDs typically include a disk for recording/reproducing data, a spindle motor to rotate the disk, and an actuator having a read/write head to record and/or reproduce data to/from the disk. The actuator can pivot around a pivot shaft, e.g., through a voice coil motor (VCM), and may further include an actuator arm rotatably coupled to the pivot shaft capable of pivoting, a slider on which the read/write head may be mounted, and a suspension installed at the actuator arm and supporting the slider for elastically biasing the read/write head over a surface of the disk. Here, the slider may be supported by the suspension by being attached to a flexure.
During the recording and/or reproduction of data, both the lift force generated by airflow formed by the rotation of the disk and an elastic force generated by the suspension act on the slider with the read/write head. Accordingly, the slider can maintain lifted above a data zone of the disk, at a height where the lift force and the elastic force are balanced. Thus, the read/write head mounted on the slider records and/or reproduces data to/from the disk while maintaining a particular gap with the rotating disk. When the rotation of the disk is stopped, e.g., when power is turned off, the lift force disappears. When the lift force disappears, the slider needs to be away from the data zone of the disk before the lift force disappears to prevent the slider from contacting and damaging the data zone. Accordingly, before the disk completely stops rotating, the actuator arm is caused to move, e.g., rotate, the slider to a parking zone, e.g., on the disk. Accordingly, even when the disk rotation is stopped, since the read/write head has been moved to the parking zone, such damage to the data zone can be prevented.
Therefore, when the disk rotation is stopped, e.g., when power to the hard disk drive is cut off, it is common for the read/write head mounted on the slider to be parked by moving the same to a parking zone on the disk, for example, before the rotation of disk is completely stopped.
Methods of parking the read/write head include a contact start stop (CSS) method and a ramp loading method. In the CSS method, a parking zone on the disk, where no data is recorded, is provided along the inner circumferential surface of the disk, and the read/write head can escape from data zones by moving to the inner circumferential surface of the disk and contacts the parking zone, where it can stay parked. However, according to the CSS method, since the parking zone needs to be provided along the inner circumferential surface of the disk, the available space for storing data is reduced. Also, when the HDD is not operating, that is, when the disk is not rotating, an external impact could be applied to the HDD causing read/write head to become separated from the disk, by the impact, and collide with a data zone of the disk. Because of this head slap phenomenon data on the disk and/or the read/write head may be damaged.
This head slap occurs when a considerable impact is applied to the HDD causing the read/write head to become separated from the disk and then collide with the disk either in the parking zone or a data zone on the surface of the disk. As a result, the disk surface may be damaged by the read/write head striking the disk surface. In addition, debris may also be scattered within the disk drive enclosure and across the surface of the disk. Although the debris may only be small enough to be observed using a microscope, since the hard disk drive is a high precision apparatus, if the debris is scattered in the data zone or interposed between the read/write head and the disk, the HDD can malfunction.
Thus, for the aforementioned portable HDDs, e.g., having diameters of 2.5 inches, 1 inch, or 0.85 inches, for example, for use in mobile environments, the ramp loading method may also be available, where the read/write head is separated from the disk and placed on a ramp structure adopted to minimize the amount of impact occurring when the HDD is not in use.
As described above, the ramp loading method parks the read/write head on a ramp installed outside of the disk. For example, FIG. 1 illustrates such a ramp where an end tab 120 portion of the suspension 114 moves to a parking zone of the ramp 130 to park the read/write head. As shown in FIG. 1, the end tab 120, upon moving into the parking zone and during the parking of the read/write head, becomes supported on a parking zone 136a on the ramp 130. Here, the ramp 130 includes a parking guide rail 135, forming a parking guide surface 136, to guide the movement of the suspension 114 when the corresponding read/write head is parked, a disk guide rail 139 located adjacent to the parking guide rail 135, an assembly guide rail 133, an end tab limiter 132 to prevent the end tab 120 from being separated from its location in the parking zone, e.g., by an external impact, and a third limiter 137 to prevent a flexure (not shown) from being separated from the parking zone, e.g., by the external impact. A predetermined section of the parking guide surface 136 is assigned to the parking zone 136a for the end tab 120.
In such a configured HDD, when the disk rotation is stopped, e.g., when the power of the HDD is turned off, a VCM (not shown) rotates the actuator arm 112, connected to a pivot shaft holder 113, clockwise. Accordingly, the end tab 120 portion of the suspension 114 contacts an inclined surface 139a of the disk guide rail 139 of the ramp 130. Next, the end tab 120 moves along the inclined surface 139a of the disk guide rail 139 and the parking guide surface 136 of the parking guide rail 135 to be placed in the parking zone 136a on the parking guide surface 136.
FIG. 2 illustrates a head stack assembly on a base where the end tab is placed at an initial assembly position of the ramp, e.g., such as in the HDD of FIG. 1. Referring to FIGS. 1 and 2, when a head stack assembly 110 is assembled on a base (not shown), for example, and while the end tab 120 is placed on the initial assembly position of the ramp 130, a shipping comb 150 may be applied to the suspension 114 to separate a plurality of end tabs, i.e., to increase the distance between each end tab so that the respective suspensions 114 are maintained at constant intervals. When the actuator arm 112 is rotated counterclockwise toward the assembly guide rail 133 to be inserted in an end portion of the ramp 130 at an inlet side thereof, the end tab 120 contacts the assembly guide slope 134, formed along an end of the assembly guide rail 133, and is guided from the assembly guide slope 134 to the parking zone 136a on the parking guide surface 136. The parking zone 136a is the initial assembly position, as an assembly position when product assembly is completed. Before the end tab 120, after moving along the assembly guide slope 134, arrives at the parking zone 136a, the shipping comb 150 may be removed by an external apparatus (not shown) in a direction indicated by the illustrated arrow shown in FIG. 2. The end tab 120 contacts the parking zone 136a on the parking guide surface 136 of the parking guide rail 135, which may be the initial assembly position. In this state, the head stack assembly 110 may be fixed through a coupling member to a base (not shown).
However, in the conventional HDD, when the head stack assembly is assembled on the base while the end tab is placed at the initial assembly position, due to various reasons such as the inappropriate aligning of the shipping comb with the suspension(s) or the head stack assembly being manufactured out of allowance, the end tab is moved to the parking zone through the entrance end portion of the ramp at an inappropriate position at which the end tab is inclined in a direction resulting in the end tab colliding with the lateral surface of the end tab limiter.
As described above, in the conventional HDD, due to various reasons such as the inappropriate insertion of the shipping comb in the suspension, when the head stack assembly is assembled on the base while the end tab is placed at the initial assembly position, the end tab may collide with the end tab limiter so that excessive torque is applied to the end tab resulting in the end tab and the flexure being deformed. Thus, the operation of the slider becomes unstable during the loading/unloading of the slider resulting in serious defects such as scratches, thermal asperity (TA), or head-media touch occurrences, which ultimately cause defects in the final product.